Pump-operating mechanism



' 1,666,227 E. G. WILLRICH PUMP OPERATING MECHANISM April 17, 1928.

Filed Aug. 1926 5 A WWW v iron/v2?! EDGAR 6. W/L ICH, r

Patented A r. 17, i928.

UN T t Pers an EDGAR G. WInnRIoH, or Los NGELEs-CALIFOR IA;

' PUMP-OPERATING MECHANISM.

Application filed'August 19, 192 Serial No. 130,302.

My invention relates to the oil producing industry and it relates particularly to oil well pumping;v equipment. J i v I A common form of" pumping equipment .used for taking oil from the ground has a a pump barrel which isplaced near the bottom of a well and which is attached to the :lower end of a pump tubing. The pump tubing extends into the well from the surface of the ground. Adapted'to reciprocate in the pump barreliis a pump plunger which is-attachedto the lower end of a string of sucker rods. The string of sucker rods ex tends through the pump tubing and a stuffing box is secured at the upper end of the pump tubing, and is connected to one end of: a walking beam pivoted on a Samson postwhich is placed on the floor of a derrick of a well. The walkingbeam is oscil-f Ylated by a walking beamcrank .whichis secured to the shaft of aiband wheel. the walk ing beam crank being operativelyconnected to the end of the, walking beam oppositeto the string of sucker rods by means" of ,a pitman. When the-walking. beam is in operation the pump plunger is reciprocated (through the interconnecting mechanism);

thus pumping oil to the surface of the ground through the pump tubing.

In the common arrangement of crank and pitman asmentioned above, the motion of the string of sucker rods is approximately simple harmonic. It is a characteristic of I I this type of motion that it is undergoing constant acceleration,- either] positive or negatlve, and that-there is therefore a con stant change in "the sucke r'rod stresses and in engine load-with peakstresses and loads at the point of maxlmiun posltive accelera- ,tion. Due to the elasticity'of the rods this peak in deep well pumping with the usual velocities, is thrown out of phase-180, and

occurs, at or near the top of the rod stroke instead of at the bottom as would be expected. Experiments have shown further 3 that the live. loadsinduced by theacceleration of therodsmaybe equal to {thedeadloads. In other words, the total loadwill be 200% of the-,dead-loa d. Furthermore,

- due-to the elastic reaction of therods, a disproportionate amount ofthe work is done by the engine-during about 45 oftherevo-" lution ofthe .crank,,fand a severe peakdoad;

is imposed onjall of thesurfaceqequipment.

. The excess*energydeli zered by theengine during; "this portion; rifathe stroke is stored its. -51

internally the rods, to be given outjlater as the peak is passed aud t-he rods contract.

These conditions cause considerable; economlc losses because of break downs ofthe equipment and concurrent loss of produc-' ti on.

' One of the foremost" deficiencies of this type of pumping equipment is the breakage of the string of sucker rods. breakage of the stringof sucker rods subjected to variable stresses is what is known This type' of I as fatigue failure? or. progressive fracture which occurs as follows. stress of a falling load, some; part of the rod where there is a local jweakness tas akink 'or a scratch on the surface of "the metal Under the which brings about a localized stress of f high intensity) will start to fail. ,Thiisfail ure will consist in a fracture of one of-the minute crystals of the metal near one of its the rod 'severs. at this placei It. has-been placed upon the sucker rods; first; itdepends upon the maximum stress, the higher the maximumstress the soonerthe breakage will take place; and, second, affunctionfof I the range of stress, thegreaterthe difference I between maximum and minimum the sooner failure will occur. g

It is an object of this invention stresses be lowered and the rangeiof maximum and vide an apparatus for operating the plung erof a reciprocatingpump ofthecharacter v v u entioned; in such a manner that the'maXL mum stress placed on. 5 the suckerrods will minimum loads will be less than in; the ordinary pumping equipment.

besatisfactor-ily obtained when the time-of the up stroke is extendedover' a greaterlpe I'lOd Of'tlIIlethan is usual practice. In my I have found that the desired'resultsmay invention I find it advantageoustomake the third reater than. that in the ordinary .cra-nkjand pitman arrangement. V I

:sAfst-illfurther objectof h's invention is,

up stroke of the plunger substantially one to providea pump operating mechanism of i l the character specified in which thewalking i beam isoperatedbya cam and followeran rangement dr ven by the ordinary band fvv'heel. I 1 u r m s d reenter ad n ge.

ofthis invention will be made evident in the following description which is taken in connection with the drawing, in which Fig. 1 is a view illustrating a mechanism embodying the features of the invention.

Fig.2 is an enlarged section taken on the line 2-2 of Fig. 1.

Fig. 3 is a view of the cam and follower arrangement of the invention taken as indi 'cat'ed' by the arrow 3 of Fig. 2 but showing the cam, in a different position.

} Fig. 41 is a section taken on the line 4l 1- of Fig. 2.

Referring particularly to Fig. 1, the numeral 11 represents a well, at the lower end of which an oil well pump 12 is placed. The oil well pump 12 has a barrel 13 which is attached to the lower end of a pump tubing 14 which extends upward to the surface of the ground and through the floor of a derrick 15. The oil well pump 12 has a plunger 16 which is attached to the lower end of a string of sucker rods 17. The string of sucker rods 17 extends upward through the pump tubing 14 and the upper end thereof is attached to a walking beam 20 which is pivoted at the upper end of a Samson post 21.

The opposite end of the walking beam has a pitman 22 connected to it. A band wheel 25 is attached toa band wheel shaft 26 which is rotatably supported by bearings 27 which are mounted at the upper ends of posts 28. Attached to one end of the band wheel shaft 26 is a walking beam crank 29. The parts which have been specified above are ordinary derrick equipment.

My invention provides a cam 32 which is secured to the walking beam crank 29. The cam 32 has a central cross bar 33 having a protruding portion which has a machined face 34: secured tightly against the walking beam crank by bolts Secured by bolts 37 to a horizontalbeam 38 of a derrick 15 is a vertical guide 39 having a vertical guide slot 40. A vertical axis extending through the guide slot 40 passes through the axis of rotation of. the cam 32 and the band wheel shaft 26. The upper end of the guide 39 is made rigid by means of a pin 42 which extends through theupper end thereof and is threadedly secured at 43 to the cam 32 on the axis of rotation thereof. The lower end of the pitman 22 is provided with an opening 45 through which a shaft 46 is extended. The opening 45 is enlarged at 17 to receive a head 18 of the shaft 46 which is rigidly secured to the lower end of the pitman 22 by suitable keys 50. The shaft 46 extendsthrough the guide slot 40 of the guide 39.

Rotatably mounted on the shaft 46 is a slide roller 53having an annular flange 54 which engages the face of the guide 39 adjacent to the pitman 22. The diameter of the slide roller 53 is such that a sliding fit is provided between it and the side walls of the guide slot 40. Placed on the shaft a6 adjacent to the slide 53 is a cam follower 55.

The cam follower 55 has a cylindrical face 56 which is adapted to engage a cam face 57 of the cam 32. Formed at opposite ends of the face 56 are rims 58, which hold the cam follower 55 and the cam 32 in proper alignment. The extended end of the shaft 16, is reduced andthreaded as indicated at 59. A

nut 60 is screwed onto the threaded end 59 up stroke of the plunger 16. l/Vhen the pit man is moved downward the plunger 16 is moved upward as is obvious from an inspection of Fig. 1. The remainder of the rotation of the band wheel is used for the down stroke of the plunger, this remainder being 120 of the rotation of the band wheel 25.

The operation of the mechanism just described is substantially as follows:

The band wheel 25 which is rotated by means of a belt 70, which belt 7 0 is driven by an engine, is set into rotation. The cam 32is revolved around the axis of rotation of the band wheel shaft 26 and the follower which follows the cam face 57 is caused to move up and down. The follower 55 is moved downward during 2&0 of the revolution of the band wheel and is moved upward during 120 of the revolution of the band wheel. The follower 55 and the lower end of the pitman 22 are caused to move up and down in a straight line by reason of the slide 53 which operates in the guide slot 40. upper end of the pitman 22, however, must swing through an a-rcuatcd path since it is attachedto one end of the walking beam 20. The pitman 22 being attached to the shaft 416 is free to rotate around its axis so that a lateral deflection of the upper end of the pitman from vertical movement is permitted The walking beam 20 reciproeatcs the string of sucker rods 17 and the pump plunger 16 is reciprocated thereby.

From the foregoing description and as prevlously explained, it Wlll be understood crank and pitman pump operating arran' ement. If desirable, the up stroke of t e plunger maybe increased and the down stroke reduced even more than the figures given. Instead of a continuously accelerated motion as is given by the crank and pit-man, my invention gives a uniform ve- The locity, consequently a uniform stress to the I rods, during substantially 180 of the 240 of the up stroke. As a result it will load the engine and belt more uniformly and re duce the live load very greatly. The live loadis reduced by reason of the fact that the maximum inertia load is considerably reduced because of the fact that the up stroke is given substantially one-third more time than is done in ordinary practice. The lineal velocity of the rods on the up stroke will only be 75% of the velocity of the rods with the crank and pitman arrangement for the samenumber of strokes per minute. The reduction of stresses and loads, however, will be in greater proportion than this because of the more uniform velocity. It willbe seen that the stress of the sucker rods is greatly reduced by lowering the maximum live load and thus decreasing the range of maximum and mlIIllIlllIll stresses which are imposed on the string of sucker rods.'

Com arin the mechanism of m invention with the ordinary'crank and pitman arrangement, the acceleration at the beginning of the up stroke'isless than that of the rick equipment.

assembly? as usedin the following claims, refers to the band wheel, the band wheel simple harmonic motion produced by the crank and pitman; and after the first 45 of travel there are twelve equal time intervals during which there isuniform velocity with no acceleration; consequently, there is no induced live load. The time allowed'for rais ing the pumpplunger in my invention is onethird longer than in the case of the ordi- "nary crank pitman but the actual load reduction, as pointed out heretofore, is considerably more than one-third because of the more uniform motion of the plunger 16 during the up stroke, being about180 ofthe rotation of the band wheel.

One important feature of the invention is that the cam and follower arrangement may be readily'used with a major part of the standard derrick equipment. The cam 32 is designed so that it may beattached to the walking beam crank 29. The guide 39 is designed so that it may be attached to one of the beams of the derrick equipment in the position shown in the, drawings. The follower guide and pin arrangement are designed sothat they may be installedat the lower end of the ordinary pitman of the clershaft, and the walking beam crank.

I claim as. my invention;

The-phrase band wheel 1 I '1'. y In combination: a pump having a pump plunger; a string of sucker rodsattached i to said plunger; a walking beam, said string of sucker rods being attached to said walking beam; a pitman joined to'said walking 7 beam; a band-wheel assembly,-a cam" con-' v nected to sa'id band-wheel assembly;'a fols lower connected. to said pitman, said follower operating on a cam face of said cam; a vertical guide; and a slidefa'ssociated with the lower end ofsaid-pitman, said slide .operat-f ing in said vertical guide. 7

2. In combinat on: a pump having a'pump plunger; a string of sucker rods attached to said plunger; a walkingbeam, said string of sucker rods being attachedto said walk ingbeam; a pitman joined to said walking beam; a band-wheel assembly; a cam connected to said band-wheelassembly; a fol-" lower connected to said pitman, said, fol-m: .l

lower operating on a camface of said cam; a vertical guide placed'belowjthe axis of r0- tation of said cam; and a-slide associated with the lower end of'said pitman, said slide operatingin said vertical guide.

. 3. In combination :-a pump plunger; a string of sucker rods attached to said plunger; a walking beam, said'string of sucker rods being attached tosaid walking beam; a pitman'joined to saidwalking beam;

having: a pump I a walking-beam crank; a .bandwheel by means of which said walking-beam crank'is rotated acam secured tosaid' wa'lking beam crank; afollower connected to said pitman, said 'followerbeing operated by said cam; a vertical guide; and a'slide associated with erating in said vertical guide.

means of which said walking-beam crank is rotated; a cam secured to said walking-beam crank; a follower connected to said pitman, said follower being operated by said, cam; .a vertical guide placed loelowtheaxisofrotation of said cam; and a slide associatedwith the lower end of said pitman, said slide ,7

operating in said vertical guide.

In testimony whereof, I have my hand at Los Angeles, California, 13th day of August, 1926. l V

hereunto set EDGAR e; warms. 

